This invention relates generally to a new device for use in orthopaedic surgery and more specifically to a new sub-trochanteric intramedullary rod system for use in fixation of fractures surgically for the purpose of maintaining the fractured portions of long bones together, and principally useful in fractures of the femur involving the sub-trochanteric and proximal shaft areas.
In the field of orthopaedic surgery, it has become common practice in many situations to use as a fracture fixation means an elongated rod or nail commonly known in the art as an intramedullary rod. Such a rod is driven into the marrow cavity or medullary passage longitudinal in a fractured bone after lateral reduction and serves to hold the severed parts thereof in longitudinal alignment incident to knitting and healing of the bone. Such nails or rods are used in treatment of long bone fractures, for example in the treatment for fracture of the femur. The nail or rod in such cases is driven percutaneously longitudinally through the tip or trochanter and into the medullary canal, and therefore serves to bridge the area of fracture in the stem on either side thereof.
Intramedullary rods are known in various forms but it has proven most satisfactory in obtaining a solid and secure joinder of fractured bones to use a rod or nail which is not subject to twisting or turning within the medullary passage of the bone. The ideal function of an intramedullary rod is to secure the proximal and distal fragments of the bone which has been fractured in correct alignment during the healing process. It should be noted that several types of loads must be transmitted from the distal to the proximal fragments. These include: compression, bending, and torsion. The compression loads are transmitted generally directly through the bone surface, while torsional and bending loads are transmitted, at least in part, by the intramedullary rod itself. In order to properly transmit torque, the rod or nail must be capable of securely gripping both the proximal and distal fragments. Additionally, the nail must be sufficiently rigid to prevent excessive bending motion at the fracture site.
The invention disclosed herein is a modification of that shown in the Burstein et al U.S. Pat. No. Re. 28,502 and has been specifically designed for fixation of sub-trochanteric femoral fractures, that is, those fractures distal to the trochanter and the femur, but proximal to the junction of the middle third and proximal third. It is recognized that sub-trochanteric femoral fractures generally occur in an area of the femur which, under normal load applications, is subjected to extremely high bending loads. The bending loads and the extremely large torsional loads present when the femur is fractured today present one of the most difficult surgical management problems in fracture fixation. Any internal fixation device to be employed for stabilizing these fractures until healing occurs, must be sufficiently strong to resist these bending loads while maintaining proper axial alignment of the bone segments.